This invention relates to seismic bracing connectors, and more particularly to a connector for use especially for connection of a seismic brace to a hanger for holding a tray for cable or electrical wire, or for holding pipe, conduit, etc. The connector is especially adapted for retrofitting existing systems of such trays or platforms with seismic bracing to inhibit undue lateral movement (sway) of the hanger in the event of seismic activity. The connector may be useful not only for such retrofit but also for original installation. It is contemplated that the connector may even have bracing connection uses other than for hangers.
Conventionally, hangers such as described for systems comprising trays holding communication cable, electrical wiring or the like or for pipe or conduit, etc. in office buildings, manufacturing plants and other facilities typically include support rods extending downward vertically from a ceiling or truss system to provide support for trays or other items in horizontal position. As such, they do not per se provide sufficient lateral support for resisting large forces, such as those induced by an earthquake. Additional seismic bracing attached to the hangers provides the added lateral support required to withstand seismic activity.
These seismic braces typically have two ends, one attachable to a support such as a ceiling or truss system and the other attachable to the hanger. Where an existing hanger is to be fitted with seismic braces, the braces are preferably connected while the support rods remain fully supportive of the hanger during installation. Moreover, it is desirable that these braces incorporate features to ensure they remain connected during seismic activity, even where a fastener securing the brace to the hanger has loosened.
Previous systems for attaching seismic bracing suffered from various drawbacks. For example, U.S. Pat. No. 5,188,317 (Roth) discloses a seismic connector 24 with a retaining clip 30. Several angle tabs 57a, 57b, 57c punched from the clip engage several slots 28, 61a, 61b in the seismic connector to keep the clip in place. During seismic activity, these tabs are prone to fail, allowing the clip to move from its proper position. Without the clip, the seismic connector no longer provides any lateral support to resist the seismic movements. Other designs incorporating tabs or other small retaining members suffer from similar drawbacks. Another disadvantage of other designs includes the use of threaded cable as a bracing member. Because cable only provides support in tension, and not compression, two opposing braces are required to support a tray. Using two supports is not always desirable because it requires twice the number of supports, as compared to a rigid support, which provides both compressive and tensive support.
Among the several objects and features of the present invention may be noted the provision of a connector for a seismic brace that permits bracing to be added without removing a vertical support rod from a trapeze-type hanger for a tray or other item; the provision of such a connector that permits bracing to be added without removing a lower retaining nut from the vertical support rod; the provision of such a connector that remains attached to a support rod during seismic activity; the provision of such a connector that will provide adequate support even where a fastener holding the connector to the support has become loosened; the provision of such a connector that reduces the number of failure modes of the connector, making the connector more reliable; and the provision of a connector that evenly distributes seismic activity forces through the connector.
Generally, a connector of the present invention for connecting a seismic brace to a support rod to inhibit movement of the rod during seismic activity comprises a metal connecting member. The member has opposite sides and opposite ends, a lower portion and an upper portion overlying at least part of the lower portion and spaced therefrom to form a gap between the upper and lower portions. The upper and lower portions are joined at a juncture at one end of the member. Openings in the juncture and in the upper and lower portions of the connecting member define a slot extending from the juncture toward an opposite end of the connecting member. The slot has an open end at the juncture for entry of the support rod into the slot and a closed opposite end. The connector further comprises a retainer for insertion in the gap between the upper and lower portions of the connecting member to a rod-retaining position in which it bridges the slot, and in which it is disposed between the juncture and the support rod when the rod is in the slot, whereby the support rod is retained in the slot by the retainer. The retainer is adapted to engage the juncture on opposite sides of the slot during seismic activity to prevent the rod from moving out of the slot.
In another embodiment of the present invention, a connector is set forth generally as above, wherein the connecting member further comprises a one-piece member of sheet metal bent to form the upper and lower portions. The retainer further comprises a metal member having a slot extending into the member from one edge thereof. The retainer slot has an open end for entry of the support rod into the slot and a closed end. The retainer slot extends generally at right angles to the slot in the connecting member when the retainer is in its rod-retaining position.
In yet another embodiment, a seismic brace system comprises a seismic brace in combination with a metal connecting member and retainer as set forth in the first embodiment. The seismic brace further comprises two ends, one attachable to a support such as a ceiling or truss system and the other attachable to the metal connecting member for bracing a support rod.
Other objects and features of the present invention will be in part apparent and in part poi nut hereinafter.